Method and apparatus for treating cementitious mixtures



Aug. 30, 1938. T. c. KNIGHT 2,128,779

METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MIXTURES Filed Feb. 19, 1937 s sheets-sheet 1 zvwenior Aug. 30, 1938. T. c. KNIGHT 2,128,779

METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MIXTURES Filed Feb. 19, 1937 5 Sheets-Sheet 2 lmllllum I All W V Even-Z 07" Aug. 30, 1938.

T. c. KNIGHT METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MIXTURES Filed Feb. 19, 1937 5 Sheets-Sheet 5 Inven'ia-r' THEODORE C. KNIGHT Aug. 30, 1938. T. c. KNIGHT METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MIXTURES Filed Feb. 19, 1957 5 Sheets-Sheet 4 Ewen/far THEODORE C. KNIGHT mmm Aug. 30, 1938. "r. c. KNIGHT 2,128,779

METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MIXTURES Filed Feb. 19, 1937 5 Sheets-Sheet 5 O 0 l0! /0! I l I 0 o I02 /02 [05 m5 v i I I 103 my M M5 Elven THEODORE C. KNIGHT Patented Aug. 30, 1938 UNITED STATES METHOD AND APPARATUS FOR TREATING CEMENTITIOUS MixToREs Theodore 0. Knight, Buffalo, N. Y. Application February 19, 1937, Serial No. 126,711 18 Claims. (Cl. 94-48) My invention relates in general to the treatment of cementitious mixtures and, for convenience in this specification, I have described my method and apparatus in connection with the making and treatment of concrete immediately following the laying of such concrete in the construction of floors, driveways, sidewalks, and the like.

While I have described my invention for use in connection with concrete, it is also adaptable in the treatment of asphalt mastic floors, hot as phalt floors, black top driveways, or any surface using a cementitious binder or binder of any kind.

It is well known to those skilled in the art that the strength, durability and other properties of concrete mixtures are governed largely by the net quantity of mixing water used per sack of cement. The less the amount of water used in a workable mixture, the greater will be the strength and durability of the resultant concrete. When finer aggregates and excess water are used in the mixture, to make hand floating easy, shrinkage is caused by such aggregate because of their bulking tendency when wet, and these aggregates in this wet mixture are brought to the surface with the excess water, which causes surface cracking, checking, and dusting, and leaves the surface with practically no wear value.

In concrete surfaces, such as floors, roads, and the like, it is desirable to have as large a quantity of the coarser aggregate as possible exposed or retained at the surface, and it is this aggregate that takes the wear more than does the cement, fine sand, or finer aggregate. It is, therefore, an important factor in the production of good concrete surfaces subject to wear and abrasion that graded, coarse aggregate be introduced into the mixture and that the mixture be relatively dry. Dryer mixtures give greater strength, watertightness' and resistance to wear, and such mixtures also permit the use of less cement. However, the use of these coarse, dry mixtures has made it very diflicult to obtain satisfactory compaction and finishing by means of hand methods or other methods previously known to the art.

One of the principal objects of my invention has been to provide a method and apparatus whereby it is possible to use a much coarser and drier mixture, having well deposited materials, than has been possible to work or float out when hand methods or when other previously known methods have been used.

Another object of my invention is to. provide an apparatus which will allow the use of leaner mixtures, thus eliminating the shrinkage factor.

A further object has been to provide an apparatus whereby a denser and more compact composition may be obtained, free from voids and impervious to liquids.

A further object of myinvention has been to insure a better bond between the layers, where a two course surface is installed, by compacting and densifying the mixtureat the bond line.

Furthermore, my apparatus makes possible the use of a mixture having an abundance of coarse aggregate at the surface, thus increasing the resistance to wear and abrasion and, thereby, eliminating cracking, crazing, and dusting.

Moreover, by means of my apparatus, the mixture is tamped while being given a thorough floating action, thereby breaking down any bridging of the aggregate that might exist, and, thus thoroughly densifying the mixture.

Furthermore, by my apparatus, impacted air and excess water are driven or brought to the surface of the mixture, thereby aiding in drying up the mixture and densifying the same.

Furthermore, the use of my apparatus causes a substantially even distribution of the materials and, therefore, does not bring to the surface any excess fine material which is detrimental to the wearing qualities of the surface and which causes surface cracking and dusting.

Moreover, my apparatus makes it possible to greatly reduce costs becauseof the use of "leaner mixtures and also because of the ease and rapidity with which the work is accomplished thereby.

Moreover, my apparatus is of such nature that the disc thereof is kept in constant contact with the surface during the treatment, thereby avoiding any sucking action which would draw the finer materials to the surface.

The above objects and advantages have been accomplished by the method herein described and by means of any one of the forms of apparatus shown in the accompanying drawings, of which:

Figs. 1 and 2 show side elevations of the preferred form of apparatus, and Fig. 3 shows a plan view of the same.

Figs. 4 and 5 show a fragmentary, side elevation and a plan view, respectively, of a modified form of invention.

Figs. 6 to 9, inclusive, show fragmentary, side elevations of various other modified forms of devices.

Fig. 10 shows a plan view of the form of apparatus shown in Fig. 9.

Figs. 11 and 12, respectively, show a fragmentary side elevation and a fragmentary plan view of another modification.

Fig. 13 shows a fragmentary, sectional, plan view of still another modification.

Fig. 14 is a fragmentary, side elevation of the form of apparatus shown in Fig. 13.

Fig. 15 is an enlarged, fragmentary, sectional view taken on line l5-|5 of Fig. 13.

Figs. 16 and 1'7 are two fragmentary, side elevations of other forms of the apparatus.

Fig. 18 is a diagrammatical view of the form of apparatus shown in Fig. 17.

/ While I have shown a number of forms of ap- /"paratus, it is obvious that the carrying out of my method may be accomplished by still other forms of apparatus.

In my invention, I use a rotary float, preferably in carrying out the form of a disc driven by an attached motor, such disc being provided with means for tamping the same while it is being rotated. By such means a rotary floating action and a simultaneous rapid tamping action is produced upon the surface of the concrete.

Referring now to the form of apparatus shown in Figs. 1, 2, and 3, a rotary float 5 is used which is preferably in the form of a relatively thin metal disc, mounted upon a shaft 6. The float is driven preferably by means of a motor I which is mounted centrally above the disc and which has its shaft (not shown) arranged coaxially with and suitably connected to the shaft 8. The device is provided with the customary operating rod 8 at the upper end of which is the usual handle 9 and a control switch it. Electricity is conducted to the switch by well known means and this connection has been omitted from the drawings for obvious reasons. A suitable electric conduit II is provided for connecting the wires from the switch III to the motor I.

Arranged above the disc 5, and rigidly connected either to the disc or the shaft 6, is a tamping ring I! which is provided with raised cam portions l6 and substantially flat surfaces I1 connecting the cam portions. Any number of these raised cam portions l6 may be provided and I have found that it is convenient to have four of them arranged in symmetrical manner.

Tamp'ing plungers II are provided which are designed to engage with the cam portions I 6 and flat portions II of the disc. In this form of apparatus, as shown in the drawings, two such tamping plungers are provided, arranged one on each side of the tamping ring. They are slidably mounted in bearing blocks I! which are secured to the base of the motor I by any suitable means or, if desired, these bearing blocks maybe made an integral part of the motor base. Each tamping plunger is provided with a stop ring 20 at the lower end and a stop ring II at the upper end. These rings or collars, in the normal operation of the plungers, do not contact with the bearing block I! but are provided for the purpose of preventing the plungers from becoming disengaged from the bearing blocks.

From the foregoing description, it will be obvious that when the disc 5 and the attached tamping ring I! are rotated by the motor 8, in this form of apparatus, each tamping plunger l8 will be raised gradually by one of the inclined sloping surfaces 22 of a coacting cam portion it until the apex of such portion is reached, whereupon continued rotation of the ring will cause the plunger to clear the apex of the coacting cam portion and allow it to fall by gravity and strike the succeeding flat surfaces I I of the tamping ring, as shown in Fig. 2, thereby giving to the disc the desired tamping action. Obviously, since the cam portions are preferably arranged in symmetrical manner, a tap is simultaneously produced by each of the plungers on opposite sides of the disc. While but two plungers are employed, as shown in Fig. 3, it is obvious that three or more plungers may be used. However. it is desirable that the number of cam portions on the tamping ring be equal to or a multiple of the number of plungers employed so that all plungers wilibe actuated simultaneously, thus evenly distributing the tamping action over the disc.

The form of apparatus shown in Figs. 4 and 5, shows the tamping mechanism comprising one or more tamping hammers 25, each of which is formed with a. head It and an arm 21. The arm 21 is formed at its inner end with a bearing portion 28 which is movably mounted upon a bearing pin 29. This pin is carried by a lug III which may be formed integrally with the casing ll of the motor. A disc 5 and tamping ring i! are employed in this form of apparatus which are substantially the same as the form Just above described. The weight of the head 26 of the hammer is such that as the apices of the cam portions it pass beneath it, the desired tamping action will be produced upon the tamping ring.

The form of device shown in Fig. 6 is substantially the same as that of Fig. 4. except that the tamping hammer 32 thereof is provided with a head 33 which is lighter than the head ll of the other form and which produces the tamping action upon the ring II partly by gravity, and partly by the use of a spring 3, instead of being actuated solely by gravity, as in the form of Fig. 4. This spring is carried by a lug 35 formed on the motor housing 36. As in the form of Fig. 4, the hammer is provided with an arm 31 and a bearing portion 38 which is rotatably supported by means of a pin 39, carried by the motor hous- 18.

In the form of apparatus shown in Fig. 7, the tamping hammer 40, having a bearing portion 44, is mounted upon the motor housing M in a manner similar to the last two forms just described. Like the form of Fig. 6, this hammer is actuated to produce a downward tamping action by a spring, in addition to gravity. The

hammer is provided with an upwardly extending arm 43 to which one end of a tension spring 42 is attached. The other end of the spring is suitably attached to an adjusting screw 45 which has a t umb head I! and a lock nut 41. The screw is carried by a lug 48 made preferably an integral part of the motor housing ll. As in the form of Fig. 6, the spring causes the hammer to be depressed and brought into contact with the tamping ring when the disc is rotated. In this particular form, the force of the tamping action may be regulated by means of the screw 4!.

Another spring-actuated form of device is shown in Fig. 8 where the tamping plunger SI is mounted in suitable bearings 8| so that it may be reciprocated vertically. The bearings, carried by the motor housing 54, are interspaced and a helical spring 52 is mounted about the plunger between the bearings and has one of its ends contacting with the upper bearing and its lower end contacting with a collar 53. It will be obvious that as the plunger is raised by means of the cam portions I I of the tamping ring IS, the spring 52 will be compressed and, when released by the movement of the tamping ring, will draw the plunger downwardly in contact with the flat portions ll of the ring.

In the form of device shown in Figs. 9 and 10, I employ a plurality of steel balls 8!, each mounted within a suitable housing I. These housings are secured to the base of the motor 51 and, for

convenience, four of them are provided. each one of which houses one of the ball plungers. By using four ball plungers. four simultaneous impacts are produced upon the tamping ring 88, which is carried by the disc N. In this form of apparatus. the tamping ring is also modified by provided with a head 98 and This arm has at its inner end a bearing 68 which having a greater number of raised portions 89 with intervening flat portions 6|.

In the form of apparatus shown in Figs. 11 and 12, I'show positive me'ansfor actuating the tamping hammers 65. Each of these hammers is with an arm 91.

is pivotally mounted upon a bolt 69. Each bolt is carried by a lug 19 formed on the housing 82 and having outwardly extending arms 1| in which an operating shaft 12 is rotatably mounted. A spring 13 is provided for each of the hammers, one end thereof being secured to the bearing 19 and the outer end pressing against the arm 61. The shaft 12 is provided with an operating arm 16 at each of its ends. These operating arms are curved, as shown in Fig. 11, and each has its outer extremity engaging the bottom ofone of the arms 61, whereby the hammers are raised when the operating arms are actuated. An eccentric lever 11 is also rigidly carried by the shaft I 12 and its lower end is connected to an eccentric Iii arm 18, which has at its inner end a band 19. The band engages with an eccentric 80 which is mounted upon the disc shaft BI. As the eccentric is rotated, it will be obvious that theeccentric arm 18 will cause the eccentric lever 11 to be oscillated back and forth which, through the medium of the operating arms 18, will cause the hammers 65 to be raised. Through the operation of the eccentric, the hammers will be moved upwardly through their maximum travel and the springs 13, which have been placed under tension during such travel, will cause the hammers to be forced downwardly when released by the operating arms 16. In this form of device, the tamping ring 14, which is carried by the disc 15, may have a smooth surface, as shown in the drawings, since the actuation of the hammers does not depend upon ridges formed on the surface of the ring, as in the other forms.

In the form of apparatus shown in Figs. 13 to 15, twotamping hammers 85 are employed, each having a head 86 and an operating arm 81, suitably mounted at its inner end upon a bolt 88 carried by a lug 83 formedon the housing 9|. Each of the arms is raised by means of an actuating cam 89 which engages with the operating arm 81. Each of the earns 89 is carried at the outer end of an operating shaft 99, suitably journalled in the housing or body 9| of the motor. A bevel gear 92 is preferably secured to the inner end of each of the shafts 99, and these gears are engageable with a bevel gear 93. The bevel gear 93 is rigidly mounted upon a vertical shaft 94 which is also journalled in the housing of the motor 9|. A spur gear 95 is also rigidly mounted upon the shaft 94 and rotatable with the bevel gear 93. The spur gear 95 is engageable with a spur gear 96 which is mounted upon the disc shaft 91. When the spur gear 98 is rotated by .means of the motor shaft, it is obvious that the shafts 99 will be rotated through the medium of the gears 95, 93, and 92, and the cams 89 will be actuated to cause the hammers 85 to be elevated. The cams are so designed that they give an elevating movement only to the hammers, and thus allow them to fall by gravity, striking the top surface of the tamping ring 98 carried by the disc 99. This tamping ring, like that in the form of Figs. 11 and 12, is smooth on its upper surface.

In the form of apparatus shown in Fig. 16, the motor I99 is so mounted as to have a slight reciprocating movement upon its vertically arranged shaft (not shown). A plurality of downwardly extending tamping arms l9| are arranged around the lower edge of the motor and each of them is provided with a tamping pad I92. The cam ring I93is carried by the rotary float I94 and is provided on its upper surface with cam portions I95 which engage with the tamping pads I92 of the tampingarmd Since the motor is considerably heavier than the plungers of the forms of apparatus hereinbefore described, it is only necessary that the motor be elevated slightly in order to produce the desired tamping action upon the float.

While all the forms of invention hereinbefore described are operated mechanically, it is possible to carry out my method by means of plungers which are actuated electro-magneticaily. In Figs. 17 and 18 I have shown such a form of apparatus. In this form, two plungers I98 are provided, each of which is slidably mounted within a. solenoid I91.

ience, I have shown a commutator II9 having a plurality of interspaced metallic contact sections III and a plurality of insulating sections II2.'

The commutator is preferably so formed that the metallic contacts thereof are electrically connected with the shaft II3 upon which the commutator is mounted. This commutator is, of course, suitably housed and protected. A brush H4 is carried by the motor housing and engages with the commutator II9. winding is preferably grounded on the shaft H3 and the other side thereof is connected to-the source of electrical energy I98. The brush H4 is connected to the other side of the source of energy. Obviously, when the brush is in contact with one of the portions N2 of the commutator, current will flow from the source I99 through the windings of the solenoids and energize the same, thus elevating the plungers I99. Just as soon, however, as the commutator rotates to such a point that one of the insulating sections H2 engages the brush, the circuit will be broken and the plungers will be allowed to fall upon the tamping ring I I carried by the float IIG, thereby producing the desired tamping action upon the float.

When either of the forms of apparatus herein shown and described is to be used, it is placed upon a newly laid concrete floor or mass which has a relatively small amount of contained moisture. As hereinbefore pointed out, my apparatus is designed to be used upon concrete mixtures which are too dry to be hand floated. The rotary movement of the float and the tamping action thereof upon the treated surface breaks down any bridging of the aggregate and thus liberates all the impacted air, as well as any excess water. Such floating and tamping thoroughly densifles the mixture and assures that the material will be securely bonded to the lower layer where a two course floor is being laid.

Instead of producing the tamping action upon the float by mechanical means or through the medium of electricity, it is obvious that the reciprocating plungers may be actuated by means of compressed air. The plungers would be actu- One side of the solenoid The solenoids are intermittently actuated by any suitable source of elecated in a manner well known to those familiar with the pneumatic hammer.

Obviously, these and other modiflcations of the details herein shown and described may be made without departing from the spirit of my invention or the scope of the appended claims, and I do not, therefore, wish to be limited to the exact embodiments herein shown and described, the forms shown being merely preferred embodiments thereof.

Having thus described my invention, what I claim is:

1. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, and means for tamping the float during its rotation.

2. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft. and means controlled by the rotation of the shaft for tamping the float during such rotation.

3. In an apparatus for treating cementitious mixtures, the combination witha shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, hammering means associated with the float, and means coacting with the hammering means for tamping the float during its rotation.

4. In an apparatus for treating cementitious mixtures, the combination with a shaft'and a motor for driving the'same, of a' disc-shaped float carried by and rotatable with the shaft, hammering means carried by the housing, and means coacting with the hammering means for tamping the float during its rotation.

5. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, hammering means carried by the housing, and means for raising and dropping the hammering means, whereby tamping action is produced upon the float.

6. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, and cam means rotatable with the float for tamping the float during its rotation.

'7. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor from driving the same, of a disc-shaped float carried by and rotatable with the shaft, hammering means carried by the housing, and cam means rotatable with the float and associ ated with said hammering means for producing a tamping action upon the float during its rotation.

8. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, a cam rotatable with the float, and means actuated by the cam for tamping the float during its rotation.

10. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a float carried by and rotatable with the shaft, a cam ring carried by the float,.a pluralityof alternate ridges and hollows formed in the upper undulating surface of said ring, and hammering means carried by the motor housing and coacting with the cam ring for tamping the float during its rotation.

11. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a float carried by and rotatable with the shaft, a cam ring carried by the float and formed on its upper surface with a plurality of interspaced, substantially V- shaped ridges, and hammering means carried by the motor housing and coacting with the cam ring for tamping'the float during its rotation.

12. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a disc-shaped float carried by and rotatable with the shaft, a pinrality of hammers having an up and down movement, and means for actuating the hammers, ghetreby a tamping action is produced upon the 13. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a float'carried by and rotatable with the shaft, a plurality of hammers having an up and down movement, and a cam carried by the float and coacting with the hammers, whereby a tamping action is produced upon the float.

14. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a float carried by and rotatable with the shaft, a plurality of pivotally mounted hammers, andlcam, means carried by the shaft and coacting with the hammers, whereby a tamping action is produced upon the float.

15. In an apparatus for treating cementitious mixtures, the combination with a shaft and a motor for driving the same, of a float carried by and rotatable with the shaft, a plurality of gravity actuated hammers, and cam means rotated by the shaft' and associated with the hammers, whereby a tamping action is produced upon the float.

' 16. A method of making and treating concrete floors, comprising making a cementitious mixture containing a relatively small amount of moisture, laying the mixture, then floating the surface of the mixture by a rotary action, and simultaneously tamping the surface thereof.

17. A method of making and treating concrete floors, comprising making a cementitious mixture containing a less amount of moisture than can be used for hand floating, laying the mixture, floating the surface of the mixture by a rotary action, and simultaneously tamping the surface thereof by means of such rotary action.

18. A method of making and treating concrete floors, comprising making a cementitious mixture containing a relatively small amount of moisture, laying the'mixture, then continuously rotating a circular, substantially rigid, metal plate upon the upper surface of the mixture to float the same, and simultaneously applying intermittently repeated blows to the rotating disc to tamp such surface.

THEODORE C. KNIGHT. 

